Circuit interrupter closing resistors

ABSTRACT

A fluid blast type electric circuit interrupter comprises a tank at ground potential containing compressed fluid (air). First and second hollow insulating columns are mounted on said tank in spaced apart relationship. The first insulating column supports six transversely arranged insulating housings and a pair of separable circuit interrupter contacts are located in each housing. The second insulating column also supports six transversely arranged insulating housings. A pair of separable isolator contacts are located in each of the two upper and each of the two lower housings on the second insulating column. A pair of separable resistor control contacts are located in each of the two middle housings on the second insulating column. All pairs of contacts are connected in series. Each pair of resistor control contacts is shunted by a closing resistor. Fluid flow control valves are located in the tank and in the two insulating columns to effect opening and closing operations of the pair of contacts of the circuit interrupter. The control valves effect an opening operation by first opening the circuit interrupter contacts, subsequently opening the isolator contacts and the resistor control contacts simultaneously, and subsequently reclosing the circuit interrupter contacts. The control valves effect a closing operation by first closing the isolator contacts and subsequently closing the resistor control contacts.

A United States Paten Clark [4 1 July4,1972

[54] CIRCUIT INTERRUPTER CLOSING RESISTORS [72] Inventor: Thomas F. Clark, Canton, Mass.

[73] Assignee: Allis-Chalmers Manufacturing Company,

Milwaukee, Wis.

[22] Filed: Dec. 10, 1970 [2]] Appl. No.: 96,887

I [52] US. Cl. ..200/l44 AP, 200/145 R, 200/148 R [51] Int.Cl ..II0lh 33/16, HOlh 33/14 [58] Field of Search ..200/l44 AP, 148 R, 145, 146

[56] 7 References Cited UNITED STATES PATENTS ABSTRACT A fluid blast type electric circuit interrupter comprises a tank at ground potential containing compressed fluid (air). First and second hollow insulating columns are mounted on said tank in spaced apart relationship. The first insulating colun'm supports six transversely arranged insulating housings and a pair of separable circuit interrupter contacts are located in each housing. The second insulating column also supports six transversely arranged insulating housings. A pair of separable isolator contacts are located in each of the two upper and each of the two lower housings on the second insulating column. A pair of separable resistor control contacts are located in each of the two middle housings on the second insulating column. All pairs of contacts are connected in series. Each pair of resistor control contacts is shunted by a closing resistor. Fluid flow control valves are located in the tank and in the two insulating columns to effect opening and closing operations of the pair of contacts of the circuit interrupter. The control valves effect an opening operation by first opening the circuit interrupter contacts, subsequently opening the isolator contacts and the resistor control contacts simultaneously, and subsequently reclosing the circuit interrupter contacts. The control valves effect a closing operation by first closing the isolator contacts and subsequently closing the resistor control contacts.

5 Claims, 5 Drawing Figures P'A'TEN'TEDJUM 1972 3,674,959

sum 1 or 2 rammu m2 3.674359 SHEET 2 BF 2 L yaw!" BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates generally to high voltage electric circuit interrupters and, particularly, to closing resistors used therein to limit current surges during contact closing operations.

2. Description of the Prior Art Some electric circuit interrupters used in high voltage power transmission systems employ closing resistors to limit current surges when the circuit breakercontacts are closed. Typically, the closing resistors are inserted in series with the circuit breaker contacts just prior to closing of the latter and are disconnected after performing their function. Insertion and disconnection of the closing resistors was accomplished heretofore by resistor control switches which were connected in series with the resistor they controlled. For example, U.S. Pat. No. 3,291,947 issued Dec. 13, 1966, to Van Sickle shows one type of gas blast circuit interrupter using a series type arrangement. Another gas blast circuit interrupter using another series type arrangement is disclosed in IEEE Transactions Paper No. 31 TP 66-1 10. Generally speaking, such series type arrangements of the closing resistor and control switch necessitate more and larger components than an improved arrangement in accordance with the present invention and result in physically larger and more costly circuit interrupters. Furthermore, difficult and costly electrical clearance and terminal arrangement roblems are presented in attempting to simplify the component arrangement in certain types of air blast circuit breakers, if the series arrangement is to be retained.

SUMMARY OF THE INVENTION In accordance with the present invention there is provided an electric circuit interrupter device, preferably of the fluid blast having at least one first pair of separable circuit interrupter contacts at least one second pair of separable isolator contacts in series with said first pair of contacts, at least one third pair of separable resistor control contacts in series with said second pair of contacts, and closing resistance means in parallel with said third pair of contacts. Operating means are provided to effect opening and closing operations of said interrupter device, said operating means effecting an opening operation by first opening said first pair of contacts, subsequently opening said second and third pair of contacts simultaneously with each other, and subsequently reclosing said first pair of contacts, said operating means eflecting a closing operation by first closing said second pair of contacts and subsequently closing said third pair of contacts. In a preferred embodiment, there are pluralities of pairs of each type of contacts and each pair is disposed in an individual housing which is mounted on one of two pairs of insulating columns which, in turn, are mounted on a grounded tank which contains compressed gas which effects contact operation by means of control valves which are located in the tank and in the insulating columns.

OBJECTS OF THE INVENTION It is an object of the invention to provide improved closing resistor means for electric circuit interrupters thereby achieving smaller, less costly interrupters having fewer components.

Another object is to provide improved closing resistor means of the aforesaid character which are especially adapted for use with fluid blast type circuit interrupters.

Another object is to provide improved air or gas blast type circuit interrupters which have the same number of breaks as prior art interrupters but employ fewer support columns to accommodate components.

Other objects and advantages of the invention will hereinafter appear.

2 DESCRIPTION OF DRAWING The accompanying drawing illustrates a preferred embodiment of the invention, but it is to be understood that the embodiment illustrated is susceptible of modification with respect to details thereof with departing from the scope of the appended claims. In the drawing:

FIG. 1 is a side elevational view of an air or gas blast circuit interrupter in accordance with the present invention;

FIG. 2 is an enlarged cross sectional view of portions of the circuit interrupter shown in FIG. 1;

FIG. 3 is a schematic showing of the arrangement and condition of contacts and resistors in the interrupter of FIG. 1 when the interrupter is in open condition;

FIG. 4 is similar to FIG. 3 but shows the interrupter after it has completed one step of a closing operation; and

FIG. 5 is similar to FIGS. 3 and 4 but shows the interrupter in fully closed condition.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows one pole or phase unit of a multiphase gas blast type electric circuit interrupter 10 in accordance with the invention. Interrupter 10 controls energization and deenergization of a multiphase high voltage electrical power transmission system and the pole unit shown is in circuit with a single phase line 12 of the system which is connected to terminals 11 and 13 of the pole unit.

The pole unit of interrupter 10 comprises a tank 14 at ground potential which contains pressurized gas, such as air, which is used for operation of the switches in the pole unit and also performs are extinguishing and electrical insulation functions, as hereinafter described. A pair of hollow insulating columns 16 and 18, such as the column 54 shown in FIG. 2, are mounted in spaced apart relationship on tank 14.

Column 16 supports six series connected circuit interrupter switches 20, 22, 24, 26, 28 and 30. The circuit interrupter switches perform the function of actually interrupting high current flow in line 12. The circuit interrupter switches are symmetrically arranged on column 16 as shown in FIG. 1 and are connected in circuit with each other as shown in FIGS. 3, 4 and 5.

Column 18 supports a first group of two isolator switches 32 and 34, two resistor control switches 36 and 38, and a second group of two isolator switches 40 and 42. Closing or surge limiting resistors 44 and 46 are supported on column 18 and are connected in parallel with the resistor control switches 40 and 42, respectively. The isolator switches perform the function of maintaining line 12 open after arc interruption by the circuit interrupter switches has occurred. The resistor control switches perform the function of inserting and removing the closing resistors. The isolator switches, the resistor control switches and the closing resistors are symmetrically arranged on column 18 as shown in FIG. 1 and are connected in circuit with each other as shown in FIGS. 3, 4 and 5. The switches on both columns are series connected by a conductor 45, as shown in FIGS. 1, 3, 4 and 5.

Each circuit interrupter switch, each isolator switch and each resistor control switch comprises a pair of relatively movable, suitably housed contacts which operate in response to gas pressure which is controlled by operating means. FIG. 2 shows the construction of a typical switch 48 which is representative of the other switches referred to herein. Switch 48 comprises housing means comprising a hollow insulator portion 50 and an electrically conductive portion 52 which is mounted on associated insulating column 54. Switch 48 further comprises two spaced apart hollow stationary contact portions 55 and 56 which are bridgable by a movable contact portion 58. Stationary contact portion 55 is connected to terminal means 60 exterior of insulator portion 50 of the housing means. Stationary contact portion 56 is electrically connected to electrically conductive portion 52 of the housing means which also serves as the means whereby switches adjacent and opposite each other on a column are connected in series with each other.

Operating means, hereinafter described, control the operation of switch 48. Referring to FIG. 2, for example, movable or bridge contact portion 58 of switch 48 is movable to open position in response to gas pressure conditions in the switch housing and is movable to closed position by a biasing spring 62. More particularly, an opening operation of switch 48 is initiated by energizing a trip coil 64 in tank 14 which releases a trip mechanism latch 66 and opens a valve 68 allowing compressed gas from tank 14 to enter a cylinder 70 and equalize the gas pressure on both sides of a piston 72 at the lower end of a tripping control rod 74. Rod 74, which is made of insulating material extends through insulator column 54 to a contact release valve 76 which is normally held closed by the gas pressure on top of piston 72 at the lower end of rod 74. When pressure on piston 72 is released by balancing the pressure on both sides of it, the rod 74 allows contact release valve 76 to open. When valve 76 opens, the gas in an annular cavity 78 behind movable contact portion 58 is released to the atmosphere. When this release of gas occurs, contact portion 58 moves, under the influence of the gas pressure in the housing means, thereby opening a blast valve 80 and separating stationary contact portion 55 and contact portion 58. The time interval between energization of trip coil 64 and contact separation is about 20 milliseconds.

In the circuit interrupters switches 20, 22, 24, 26, 28 and 30 and in the resistor control switches 36 and 38 constructed in accordance with typical switch 48 shows in FIG. 2, the are that is initiated as the contacts open is transferred to the two stationary contact portions 55 and 56 where are products are blasted away by the gas flowing through the orifices therein and arc interruption is accomplished.

A closing operation of switch 48 is initiated by supplying gas pressure to a cylinder 82 to effect resetting of trip latch 66 and valve 68. Pressure on top of piston 72 caused by a decrease in gas pressure in cylinder 70 caused downward movement of rod 74 and closes contact release valve 76 allowing slidable contact 58 to close. Such closure shuts blast valve 80 and recloses the switch contacts 58 and 80.

Circuit interrupter 10 operates in the following manner. Assume that interrupter I is in the open condition shown in FIG. 3, i.e., that the circuit interrupter switches 20, 22, 2A, 26, 28 and 30 are closed and that the isolator switches 32, 34, 40 and 42 and the resistor control switches 36 and 38 are open. In this condition there is no current flow between the terminals I I and 13 ofinterrupter I0.

interrupter I0 is closed by first effecting simultaneous closure of the isolator switches 32, 34, 40 and 42 thereby connecting the closing or surge limiting resistors 44 and 46 in circuit as shown in FIG. 4. After the resistors perform their function, the resistor control switches 36 and 38 are closed to shunt the resistors 44 and 46 and effectively remove them from circuit as shown in FIG. 5. When this occurs current can flow between the terminals 11 and 13 of interrupter l0.

Interrupter 10 is opened by first effecting simultaneous opening of the circuit interrupter switches 20, 22, 24, 26, 28 and 30. After an interval of time about three to four times the maximum expected arc interruption time of the interrupter switches, the isolator switches 32, 34, 40 and 42 are opened and simultaneously with the opening of the isolator switches the resistor control switches 36 and 38 are opened. After a suitable interval of time following opening of the isolator switches and the resistor control switches, the circuit interrupter switches 20, 22, 24, 26, 28 and 30 reclose and interrupter 10 assumes the open circuit condition shown in FIG. 3.

In a preferred embodiment of the invention, for example, interrupter 10 would be rated at 500 KV, 38,000 MVA. Maximum resistor current would be 350 amperes. Breaker closing time would be 7.5 cycles l 25 milliseconds).

Circuit interrupters in accordance with the present invention could employ types of switches and operating means other than those shown in connection with FIG. 2. However,

the types shown in FIG. 2 are well suited for use in air or gas blast circuit interrupters of the type shown in FIG. 1.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In an electric circuit interrupter device,

at least one first pair of separable circuit interrupter contacts,

at least one second pair of separable isolator contacts in series with said first pair of contacts,

at least one third pair of separable resistor control contacts in series with said second pair of contacts,

closing resistance means in parallel with said third pair of contacts,

and operating means to efiect opening and closing operations of said interrupter device,

said operating means eflecting an opening operation by first opening said first pair of contacts, subsequently opening said second and third pair of contacts simultaneously with each other, and subsequently reclosing said first pair of contacts,

said operating means effecting a closing operation by first closing said second pair of contacts and subsequently closing said third pair of contacts.

2. In a fluid blast type electric circuit interrupter,

a tank at ground potential containing compressed fluid,

first and second hollow insulating columns mounted on said tank in spaced apart relationship,

at least one first pair of separable circuit interrupter contacts mounted on said first column,

at least one second pair of separable isolator contacts mounted on said second column and in series with said first pair of contacts,

at least one third pair of separable resistor control contacts mounted on said second column and in series with said second pair of contacts,

each of said pair of contacts being located in a hollow housing mounted on a respective insulating column,

closing resistance means mounted on said second column and in parallel with said third pair of contacts,

and operating means to effect opening and closing opera tions of said circuit interrupter,

said operating means comprising fluid flow control valves located in said tank and in the hollow contact housings,

said operating means effecting an opening operation by first opening said first pair of contacts, subsequently opening said second and third pair of contacts simultaneously with each other, and subsequently reclosing said first pair of contacts,

said operating means effecting a closing operation by first closing said second pair of contacts and subsequently closing said third pair of contacts.

3. A circuit interrupter according to claim 2 which comprises a plurality of first pairs of contacts which are series connected with each other and are mounted on said first column,

a plurality of second pairs of contacts which are series connected with each other and are mounted on said second column,

a plurality of third pairs of contacts which are series connected with each other and are mounted on said second column,

and a plurality of closing resistance means mounted on said second column.

4. A circuit interrupter according to claim 3 wherein each of said pairs of contacts is located in a separate hollow insulating housing which extends transversely from its supporting column.

5. A circuit interrupter according to claim 4 wherein there are six first pairs of contacts, four second pairs of contacts, two third pairs of contacts and two closing resistance means. 

1. In an electric circuit interrupter device, at least one first pair of separable circuit interrupter contacts, at least one second pair of separable isolator contacts in series with said first pair of contacts, at least one third pair of separable resistor control contacts in series with said second pair of contacts, closing resistance means in parallel with said third pair of contacts, and operating means to effect opening and closing operations of said interrupter device, said operating means effecting an opening operation by first opening said first pair of contacts, subsequently opening said second and third pair of contacts simultaneously with each other, and subsequently reclosing said first pair of contacts, said operating means effecting a closing operation by first closing said second pair of contacts and subsequently closing said third pair of contacts.
 2. In a fluid blast type electric circuit interrupter, a tank at ground potential containing compressed fluid, first and second hollow insulating columns mounted on said tank in spaced apart relationship, at least one first pair of separable circuit interrupter contacts mounted on said first column, at least one second pair of separable isolator contacts mounted on said second column and in series with said first pair of contacts, at least one third pair of separable resistor control contacts mounted on said second column and in series with said second pair of contacts, each of said pair of contacts being located in a hollow housing mounted on a respective insulating column, closing resistance means mounted on said second column and in parallel with said third pair of contacts, and opeRating means to effect opening and closing operations of said circuit interrupter, said operating means comprising fluid flow control valves located in said tank and in the hollow contact housings, said operating means effecting an opening operation by first opening said first pair of contacts, subsequently opening said second and third pair of contacts simultaneously with each other, and subsequently reclosing said first pair of contacts, said operating means effecting a closing operation by first closing said second pair of contacts and subsequently closing said third pair of contacts.
 3. A circuit interrupter according to claim 2 which comprises a plurality of first pairs of contacts which are series connected with each other and are mounted on said first column, a plurality of second pairs of contacts which are series connected with each other and are mounted on said second column, a plurality of third pairs of contacts which are series connected with each other and are mounted on said second column, and a plurality of closing resistance means mounted on said second column.
 4. A circuit interrupter according to claim 3 wherein each of said pairs of contacts is located in a separate hollow insulating housing which extends transversely from its supporting column.
 5. A circuit interrupter according to claim 4 wherein there are six first pairs of contacts, four second pairs of contacts, two third pairs of contacts and two closing resistance means. 